a524: 手機之謎. FYI: https://yunlinsong.blogspot.com/2016/02/a524.html

a524.cpp

#include <cstdio>
#include <algorithm>

using namespace std;

int main() {
    int n;

    while( scanf("%d", &n) != EOF ) {
        int *number = new int[n];
        for( int i = 0; i < n; i++ )
            number[i] = n - i;

        do {
            for( int i = 0; i < n; i++ )
                printf("%d", number[i]);
            printf("\n");
        } while ( std::prev_permutation(number, number + n) );

        delete number;
    }

    return 0;
}